<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>首页</title>
  </head>
  <body>
    <h1>尚硅谷</h1>
    <button>点击获取用户数据</button>
    <script>
      const btn = document.querySelector('button')

      btn.onclick = function () {
        const x = new XMLHttpRequest()
        //这里因为是满足同源策略的, 所以 url 可以简写
        x.open('GET', '/data')
        //发送
        x.send()
        //
        x.onreadystatechange = function () {
          if (x.readyState === 4) {
            if (x.status >= 200 && x.status < 300) {
              console.log(x.response)
            }
          }
        }
      }
    </script>
  </body>
</html>
